Suspension polymerization process

ABSTRACT

Suspension polymerization of branched block conjugated diene/monovinyl substituted aromatic copolymers dissolved in vinylidene group containing monomers, such as styrene and acrylonitrile, results in high impact plastic compositions without need for crosslinking.

United States Patent [191 Childers et al.

[ Sept. 2, 1975 SUSPENSION POLYMERIZATION PROCESS [75] Inventors:Clifford W. Childers; Earl Clark,

both of Bartlesville Okla [73] Assignee: Phillips Petroleum Company.

' Bartlesville. Okla [22 Filed: Nov. 15,1972

21 Appl. No: 306.592

[52] US. Cl 1. 260/880 B [51] Int. Cl. C08f 19/08 [581' Field of Search260/880 B. 879

[56] References Cited UNITED STATES PATENTS 328L383 10/1966 Zelinski ct11 260/880 B 3.442.981 5/1969 Stafford ct al. 260/880 B 3,485.89412/1969 Porter 260/880 B 3.536.784 10/1970 Skendrovich ct al. 260/880 B3,637,554 1/1972 Childers 260/880 B Primary E\tlHliIILl'-JOS]J11 L.Schofer ASS/SHIN! E.\'uminer-P. R. Mich] [57] ABSTRACT 22 Claims, N0Drawings SUSPENSION POLYMERIZATION PROCESS The invention relates to highimpact plastic compositions. In another aspect. the invention relates tosuspension polymerization systems.

BACKGROUND OF THE INVENTION Polymerization of vinylidenegroup'containing monomers in the presence of elastomers has beenpracticed utilizing latex systems. bulk polymerization systems. bycombination methods in which vinylidene groupcontaining monomers arebulk polymerized to a low degree of conversion and the partiallypolymerized mixture then emulsified. or put into a suspension, forfurther polymerization. or by polymerizing a rubbcr-inmonomer solutionin a suspension polymerization system by means of a peroxide initiator.

The product obtained has been required to be crosslinked in a subsequentstep in order to obtain desired high impact strength characteristics.Such added step heretofore has been a necessary, but expensive addedmanufacturing cost.

Needed are simplified processes for producing high impact plasticcompositions. Simplifying the number of steps. or reducing the number ofmaterials to be employed. yet producing high impact plastic compositionsclearly would be desirable from a practical and com mercial standpoint.

OBJECTS OF THE INVENTION It is an object of the invention to providenovel high impact plastic compositions. It is a further object of theinvention to provide a novel process for the production of high impactplastic compositions.

Other aspects. objects. and the several advantages of our invention willbe apparent to one skilled in the art from the following disclosure andour appended claims.

BRIEF DESCRIPTION OF THE INVENTION By utilizing branched blockelastomeric copolymers dissolved in a vinylidene group containingmonomeric mixture to form a rubber-in-monomer solution. and polymerizingthis rubbcr-in-monomer solution in a suspension system. a polymericproduct is produced which exhibits a desirable high impact naturewithout need for a subsequent crosslinking step. Thus. our process issimpler and more economical. and. as can be seen from data included inthis disclosure. more effective or at least as effective as more complexmethods as far as the resulting high impact plastic composition isconcerned.

DETAILED DESCRIPTION OF THE INVENTION Branched block rubbery copolymersare dissolved in a vinylidene group-containing monomer medium,preferably a monovinyl-substitutcd aromatic compounds/polymerizablcnitrilc monomer mixture. The resulting rubber-in-monomer solution thenis suspension polymerized utilizing a free radical initiator for graftcopolymerization of the polymerizable monomcrs. The resulting polymericproduct is recovered in bead form from the suspension polymerizationprocess. and can then be used for a variety of product formulations.

The branched block copolymers suitable for the process of our inventionmay be characterized as radial block copolymers. These branched blockpolymers are copolymers of at least one conjugated diene and at leastone monovinyl-substituted aromatic compound.

are rubbery or clastomeric. and are unsaturated at least to the extentof having at least enough unsaturation to be characterized asvulcanizable.

The end groups of the branched block copolymers preferably are styreneor substituted-styrene end groups. Utilizing branched block copolymerswith sty rene end blocks or groups avoids gelation during the suspensionpolymerization. reduces solution viscosity for use in processing. andapparently tends to facilitate formation of graft copolymers in theprocess where one of the polymerizablc monomers is arnonovinylsubstituted aromatic compound. These branched block rubberycopolymers should have a suitable branch length to achieve the desiredproperties in the grafted product. though the branch lengths can varysomewhat depending on the monomers and the intended use of the finalgraft copolymer. I I l The branched block copolymers. characterized asrubbery and unsaturated. contain at least one copolymerized conjugateddiene and at least one copolymerized monovinyl-substitutcd aromaticcompound. Any conjugated diene polymerizable with an alkali metalinitiator. organolithium preferably. or organosodium. -potassium.cesium. -rubidium. all as are known in the polymerization arts. can beutilized; and any copolymerizable monovinyl-substituted aromaticcompound polymerizable with such initiators can be utilized.

The more readily available polymerizable conjugated dienes contain 4 to12 carbon atoms per molecule and preferably from a commercial standpointare those of 4 to 8 carbon atoms per molecule. particularly 1.3-butadiene. isoprenc. and piperylene. though such as2.4-dimcthyl-1.3-butadienc. l.3-octadicne. 4.5-diethyll.3-octadiene. andthe like. can be utilized. alone or in admixture or by sequentialpolymerization.

The copolymerizable monovinyl-substituted aromatic compound can be anypolymerizable monomer of this class copolymerizable with the conjugateddiene employing an alkali metal-based initiator. such as those of 8 to20. more particularly for commercial availability 8 to l2. carbon atomsper molecule. including the presently preferred styrene. various of thealkyl styrenes such as B-methylstyrene. 3-ethylstyrene.4-npropylstyrene. 4-cyclohcxylstyrene. 4-decylstyrene.2-ethyl-4-benzylstyrene; the alpha or beta-substituted styrene suchalpha-methyl styrene and l propenylbenzene; and also l-vinylnaphthalene.and similar derivatives of the vinylnaphthalenes as have been describedfor the styrenes; and the like. alone or in admixture. or by sequentialaddition.

The polymerizable conjugated diene. one or more. and the polymerizablemonovinyl-substituted aromatic compound. one or more. are polymerizedwith an organomonoalkali metal initiator by processes known in the art.such as by sequential addition. so as to produce a block copolymercontaining an active alkali metal atom. e.g.. a carbon-alkali metalbond, on the conjugated diene end of the polymer chain.

Among the suitable organoalkali metal initiators are those which can berepresented by such as RLi in which R represents a hydrocarbyl radicalof aliphatic. cycloal iphatic, or aromatic nature, of up to about 20carbon atoms per molecule. although higher molecular weight initiatorscan feasibly be employed. Examples include methyllithium. the presentlypreferred n-butyllithium. or others as known in the art. Use of theinitiators. amounts. and the like. in preparation of suitable blockcopolymers is known and need not be repetitiously re peated here.Polymerization temperatures. controls. methods. also are known and neednot be further described.

The amount of polymerizablc conjugated diene employed in preparingtheblock copolymer can vary about to )5 parts by weight per 100 parts byweight of monomers employed. the'remainder being substantiallycopolymerizable 'monovinyl-substituted aromatic compound. Preferably,the block copolymer contains about to parts by.weight of polymerizedconjugated diene per l00'parts of total polymerized monomcr.

At the conclusion of the polymerization to prepare the block copolymer.a polyfunctional treating agent which contains at least three reactivesites is added to the unqucnched. i.e.. otherwise unterminated. reactionor polymerization mixture. The polyfunction com pound contains at leastthree. preferably 3 to 7. reactive sites capable of reacting with thecarbon-lithium bond on the end of the conjugated diene block of thepolymer chain and adding to the carbon possessing this bond. Theresulting polymer is a radial or branched block copolymer havingbranches which can be visualized as radiating from a nucleus formed bythe poly functional compound. with the blocks of polymerized conjugateddiene of the block copolymer toward the center of the radial blockpolymer. and the polymonovinyl aromatic compound blocks of the blockcopolymer at the outer extremities.

Conditions for the coupling or branching reaction are known in the artand need not be recited here. being fully described by Zelinski andHsieh in U.S. Pat. 3.28 l .383. patented Oct. 25. 1966. and by Childersin U.S. Pat. 3.637.554. patented Oct. 25. 1972. The polyfunctionalagents used to form the radial block copolymers include such aspolyepoxides. polyisocyanates. polyimines. polyaldehydes. polyhalidessuch as the silicon or tin tetrahalides. and the like. The amount ofpolyfunctional treating agent can vary. but preferred for most efficientcoupling is a range of about 1 to 1.5 equivalents of treating agentbased on the lithium or other alkali metal present in the polymer.

After coupling. the now-branched polymer can be recovered from thepolymerization mixture by conventional methods. such as terminating withwater. acid. alcohol. or other. removal of solvent. drying. and thelike.

In the practice of our process. the branched block co polymers aredissolved in vinylidenc group-containing monomers. The vinylidenegroup-containing monomers include vinyl-substituted aromatic compounds.alpha. beta-unsaturated nitriles. esters of acrylic acid. esters ofalkacrylic acid. vinyl esters such as vinyl acetate. vinyl butarate. andthe like. The number of carbon atoms per molecule in such monomersranges from 3 to 30 or more carbon atoms per monomer molecule. presentlypreferably up to 18 carbon atoms per molecule. more preferably foravailability up to 12 carbon atoms per molecule. These monomers include.for example. the presently preferred styrene plus either acrylonitrilcor methacrylonitrile'. as alphamcthylstyrene. methyl methacrylatc.4-vinylbiphcnyl. Z-vinylnaphthalene. and the like. Other useful monomers include the maleinimides and olcfinically unsaturated hctcrocycliccompounds polymerizablethrough the olcfinic unsaturation. Relatedmonomerssuch as well as the dialkyl maleates or fumarates also areuseful within the context of this invention. Mixtures of monomers may beemployed.

The amount of the branched block copolymer dissolved in the vinylidenegroup-containing monomer or monomers can be of any broad range suitableor desired depending on the particular branched block copolymer-andmonomer characteristics. For commercial convenience in materialshandling in suspension polymerization processes. a range of about 5 to40 percent by weight based on the combined weight of branched blockcopolymer and monomers presently is considered suitable and convenient.Presently preferred are the use of monomer mixtures in which avinylidene nitrile-containing monomer is one componentthereof andconstitutes up to about weight percent ofthe monomer mixture excludingrubber. Especially useful products for many purposes may be obtained bytheuse of monomer mixtures containing 0 up to about 50. preferably 0 toabout35, parts by weight'of acrylonitrile per parts of monomer mixture.Thus. preparation of impact polystyrenes is included within the scope ofour invention.

Chain transfer agents may be added. if desired. to the polymerizationmixture for molecular weight control of the polymer. Chain transferagents include the alkyl. n-. sec-. or tert-. mercaptans preferablyhaving 4 to lo carbon atoms per molecule. such as t-dodecyl mercaptan.n-dodecyl mercaptan. and the like. Other useful agents include nonalkylmercaptans; the lower alkyl xanthogens such as diisopropyl xanthogen;alpha-bromoethylbenzene. alpha-chloroethylbenzene. carbon tetrabromide;alpha-methylstyrene dimer; and the like. Such modifiers can be added inanamount sufficient for the effect desired. typically about 0.4 to 1.5weight percent of the total weight of polymerization mixture.

The amount of water employed in suspension polymerization can varywidely depending on the reactor employed. agitation means. and the like.It presently is preferred to employ sufficient water such that in thefinal suspension mixture water represents about 20 to 80 percent byweight of the total polymerization mixture including water. The timeemployed for polymerization is that sufficient for the conversiondesired. varies depending on other reaction parameters such thetemperature chosen. and can range from a very few minutes to such as 48hours or more. preferably at least 2 to 16 hours. The temperatureemployed in the suspension polymerization is at least sufficient toinduce decomposition of the free radical initiator. A suitable expedienttemperature range is from about 50 to Although the suspensionpolymerization reaction may proceed thermally. it is preferable toincorporate into the polymerization system a free-radical generatinginitiator. initiators useful in the context of this invention includethe monomer-soluble organic peroxides. such as di-t-butylperoxide.bcnzoyl peroxide. lauroyl peroxide. toluyl peroxide. t-butylperacetate. tbutyl perbenzoate. dicumyl peroxide 2.5-dimethyl-2.5- di(t-butylperoxy )hexane. 2.5-dimethy'l-2.5-di( tbutylperoxy)hexyne-3.t-butyl hydroperoxide. cumene hydroperoxide. p-menthane hydroperoxide.cyclopentane hydroperoxide. diisopropylbenzenc hydroperoxide. pinenehydroperoxide. 2.5-dimethylhexane-2.5- dihydroperoxide. and the like.and mixtures thereof; as well as any ofthcmonomer-soluble azo initiatorsuseful in suspension polymerization systems azobis(2-methylpropionitrile 3.2 '-a7.obis( 'lmethylvalcronitrile). and thelike. and mixtures. The quantity of initiator employed usually rangesfrom such as 2.2-

and allowed to dissolve in styrene/acrylonitrile monomer mixturesolution at 2550 C. after which other ingredients were added as per thefollowing polymer solution composition:

Polymer Solution ('ompositiun Parts b \Neight Runs 1 .1 4

Rubber empl yed I; l) Amount l5 l' l* Sly rene auylnnilrile 30 5 N5 N)(ycluht-sane b5 (I (I t Dodet;lmclcaplan {chain transfer agent! I l 0.5.5

t5 Butyl pew-ctoate l inlliator) ll 1 0.4 o 4 (r4 The following examplesare intended to further illustrate our invention and to as. st thoseskilled in the art to a further understanding of our invention.Particular runs. exemplary species. amounts, and the like. are in'tended to be illustrative and not limitative of the reasonable andproper scope of our invention.

EXAMPLE I t A series of runs was conducted in which 75/25 weight ratiobutadienc/styrene block copolymers were prepared and coupled to affordvarious degrees of branching, and then employed. in accordance with theinvention. as the rubbery component in the preparation of ABS graftcopolymers by suspension polymerization.

5 A suspension-dispersion formulation was prepared as fol lows:

Suspensitvii-Dispersion Formulation Parts by Weight Water rm, NadO, I2 H0 t'atL-l H. .o

Water (asein derivative Separate aqueous solutions of sodium-phosphateand of calcium chloride were prepared at about C. and then combined toprecipitate finely divided calcium phosphate as suspending agent. Aftercooling. Cascoloid ST56. a casein derivative from Borden Chemical Co..was added.

Each respective polymer-solution composition and thesuspension-dispersion formulation were combined and the respectivemixtures agitated-at about 80 C. for

8 hours. After suspension polymerization. each mixture was acidifiedwith dilute hydrochloric acid. and the ABS graft copolymers. obtained inthe form of small beads. were water-washed. collected by filtration. and

" dried at about 80 C. under reduced pressure.

A gram sample of each of the graft ABS copolymer l. 2. 3. and 4 wasdivided into two 65 gram portions. Each such portion was milled undernitrogen in a Brabender Plastograph at 210 C. at 10 rpm untilPREPARATION OF BD/S BLOCK COPOLYMERS Coupled 75/25 butadiene/styrenecopolymers were prepared by the recipe shown below. The ingredients arelisted in the charge order used.

(yclohesane plnn' fluxing occurred. Then; to each portion of each graftA portion ofeach butadic ne/styrene rubbery block cocopolymer thus inthe molten state was added a stabiliw polymer A. B. and D was dividedinto small pieces 'I ABILE u A395 (rral'tetl ('o nlymer Properties ingadmixture of 0.65 gram of an antioxidant mixture (0.13 gram of2.6-di-t-butyI-4-methylphenol. 0.303 gram oftris(nonylphenyl)-phosphite. and 0.2l6 gram ofdilaurylthiodipropionate). and 0.33 gram of calcium stearate asprocessing aid. To one sample of each pair of graft copolymer portionsalso was added 0.065 gram of dicumyl peroxide. Thus. each pair thenrepresented one composition l-a. 2-a. 3-a. 4-a. according to theinvention, and one composition l-b. 2-b. 3-b. 4-b to be further milledwith dicumyl peroxide as taught by the prior art in order to obtaincomparative test data showing the effects of peroxide treatment of graftcopolymers as is presently conventional required practice. Each suchportion. whether ornot it contained the peroxide. then was milled inaBrabcnder Plastograph at 2l0 C. for 3 minutes at 150 rpm.

The weight average molecular weight. degree of branching. and inherentviscosity values were determined for each ungrafted rubbery blockcopolymer A. B. C. D and appear in Table 1 below:

Conversion in each graft copolymerization run was. 96-95 weight percent, based on the weight conversion of styrene-acrylonitrile.-

The data in Tablell above reflects a maximum izod impact value for runsof the invention l-a. 3-a. 4-21 at the tri-chain branching level. and aminimum at the hexa-chain level. As shown in Table l, the molecularweight of each block copolymer employed A. B. C. D was essentiallyconstant. and thus the length of each. branch of the block copolymerswas less with an increase in the number of branches per molecule. Thebranch length in the hexa-chain product was too low for optimumperformance.

EXAMPLE ll A further series of runs was made employing 75/25butadiene/styrene rubbery block copolymers as the rubbery component inpreparation of ABS plastic resins by suspension polymerization. In thepreparation of 75/25 butadiene/styrene block copolymers. the generalprocedure of Example I was'followed. using the following rccipez' Block('opulynier Recipe Rubber 1: I (i H I I \'t:lohe\anev phm 22 722 722 722722 722 Styrene. pb\\ 25 25 25 25 25 25 'l'etrahydrol'uran. phm 0 l 0.1U.l 0.l 0.l (LI ltutyllithiuln. nihm I R o 0.33 l 2 l'emp.'(. l'or |H l\lll. ulstyrene block 70 7U 70 70 70 -7() 'l'ime. hr. I'm polym.ol'styrene block 05 0.5 (1.5 s (I)? 0.5 liutadiene. pb\\ 75 75 5 75 7575 Temp. (I for polym. of butadiene block 70 7o '.'(1 To To 7o lime. hr.I'm P l \l'll. of butadiene block I I l l l l ('oupling agent. mhm none1"" I" none 0.33"" 0.33"" l -di-t-butyI-methylphenol. phm l.h I.o !.h lb l1 1.!

""Metln ltriclilornsilane ""l le\aclilurodisilane TABLE I Block(opolymer Properties Butadiene/ Rubber Styrene Number of No. Ratio M,,.l0 Branches"" l.\'."

A 75/25 223 2 l.(\. B 75/25 23*) 3 Hi4 75/25 275 4 L l) 75/25 224 h I.I4

"Numbe| oI- branches in branched polymer determined by gel permeationchromatograph ""lnherent Viscosit} determined in tetrahy\lrofuranolution Each grafted and milled ABS copolymer l-A. I'll. 2-A. 2-8. 3-/\.3-B, -l-A. 4-B sample was testcd'for \'ari-- ous properties. withresults as shown below:

Physical properties of the several ungrafted block copolymer rubbers Ethrough 1 inclusire'x'vere determined as per Table III below:

TABLE 111 Block Copolymer Properties the superiority of the graftedcopolymers runs 9-a and IO-a of the inventive graft copolymers overthose made with dicumyl peroxide in the hot mixing peroxide cross-Bututliene/Stvrene Number of Rubber Ratio M,,. l(1 Branches IV. lmkmgStep and E 75/25 117 1 1.11 EXAMPLE III F 75/25 11111 i 3 11. 14 (.175/25 11114 11 11.115 Further runs were made employmg a 75/25 butadic- H75/25 4111 1 2.5.1 I 75m :77 3 W4 tic/styrene random copolymer as therubbery compo- J 75 3112 11 1.311 m nent 1n the ABS system. Otherwise.the procedures as described in Example I for preparation of the polymerand subsequent suspension graft polymerization were Eflch grilficdfmdfmucd copolymcr was wstcd for followed, except that a randomizing agentwas added Varlous P 9P Wlth Tcsults shown below: with the monomers forpreparation of the copolymer. 15

TABLE IV ABS (iral'tcd (opolxmcr Properties l/111l (irull Prepared MeltFlo Fle\ur:1l Impact Run From 21111 L. Modulus 'Iensile Flungullulll'1.lb.s No. ('o 1ol \n1e1' 5 Kg Psi X I11 I Psi '1 in \oleh 5-11 F.11.11 1 311 1 114411 1 1 11,5 5.11 11.14 71-1? 111411 :5 :.s 11-11 F1|.I5 354 (1471) I5 3.3 11-11 113s 3-13 1 41111 31 2.11 7-11 11 11.411 s11 1311 111 11 741 11x 1 325 11-11111 11 2.2 s-11 H 11.57 3 1 57711 152.: s4 11.5 33 3 5:711 111 3.1 1-11 1 11-117 3-1 112311 22 4.5 1.111,711 3;: 57511 311 2. 1 I1111 1 11.1 1 333 1121111 $3 7 5 111-11 11.41 31. 55711 5.x

The data in Table IV indicate that among graft co and the followingpolymerization recipe was employed:

Random (11 1111 111e1' Recipe Rubber K I. M N (yclohexanm phm 721 II 722722 Styrene. pbw Z5 '5 25 25 25 Butadienc pbw 7; -1 75 75 75'Ietrahylrol'urnn. phm 3 3 n-Butyllithiumr mhm 11.5 1.11 l5 2.11 3.11Polymeriyation Temp. (1 71) 711 711 711 711 Polymerization 'l'ime. hrs.1 l l l l Coupling Agent. mhm 11 11.5"" 11.5 11.1125 11.5"" I.b-LILZ-but'I--I-meth lphenol. phm l.11 1.11 1.11 l.11 1.11

""Dimclh)ldichlurnsilum:

""Silicone tetrachloride; 11.375 added in one increment lolloot-d byfour inerenlen'ts ol 11.11112 each added :11 one minute lntenals ""Ilcxaelllorodi iliule polymers 5-a. 6-a. and 7-a. the maximum Izod impactThe rubbers K through 0 then were dissolved in value occurs with thetri-chain structure. 6-a. and the minimum value occurs with thehcxa-chain structure. i 7-a. for reasons discussed in Example I. Theimpact performance values of the graft copolymcrs 6-a and 7-a areinferior to those of corresponding graft copolymers 2-a and 4-21 shownin Table I]. in view of the lower molecular weights and. thereforeshorter chain branches present in copolymcrs F and G. The polymers E andH were not branched or coupled since no coupling agent was employed asper recipe given. In runs with rubbers H. l. and J, impact performanceimproved with increased branching since the molecular weights weresufficiently. high to afford branches of effective length even in theinstance of the hea -chainstgueture. Note styrcne/acrylonitrile 70/30monomer mixture to the extent of 15 per cent rubber and per centmonomermixture. and polymerized in a suspension polymerization system. all asbefore described. Conversions of -94 per cent were obtained in each runrelative to the styrene and acrylonitrilc. The graft copolymers runs l Ithrough 15 prepared using random copolymcr K through 0 respectively weredivided into two portions. withfone portionof each crosslinkcd withadded dicumyl peroxide. as described hereinbeforo and all portionshot-milled. v

'The"rahdom'copolymer rubbers K through 0 were ck-111111 11611 forproperties as before:

TABLE V Random ('opolymer Properties I Number of Rubberllutadiene/Styrene M,, 10 Branches l V.

K 75/25R"" 2-10 1 1.78 l. 75/25R 19-1 2 149 M 75/25R 213 3 1.32' N75/25R 262 4 1.2-1 75/25R 22 (1 1,011

""Randuni -T.l 1e following results were obtained upon examina tion ofthe grafted hot-milled polymers:

The rubbery polybutadienes P through T were examined with the followingresults:

TABLE v11 Homopol mer Properties Polybutadiene Number of Run No. M I1(1Branches l V.

P 227 1 2.18 Q 1117 2 1.92 R 187 3 1.79 S 193 4 1.47 1 195 (1' 1.19

The above results with Runs 12-a. 13-a. 14-a. l-a clearly show thenonsuitability of the use of branched random but-adiene/styrenecopolymers in the process of our invention in place of the branchedblock copolymers illustrated in Examples 1 and 11.

tively were recovered. Conversion was 94-96 percent in each run relativeto the conversion of styrene and aerylonitrile. The grafted copolyrners16 through 20 each was divided into two portions (1 and h; to the bportion of each pair then was added dieumyl peroxide as described inExample 1. each sample a and-;h then subjected to the hot-milling stepas deseribed reyiously. and finally stabilized.

Grafted These grafted hot-milled rubbers were examined with thefollowing results obtained:

TABLE Vlll ABS Graft (opolymer Properties EXAMPLE IV Pre ared Run FromMelt Flexural Ten- Elong- Izod Further runs were made usmg a rubberypolybutadi- N R r Flow Modulus silc m mp ene homopolymer as the rubbencomponent. The rub- )l h t I "H I 16-11 (1.06 347 6070 13 2.2 l e y pt uat 1cm. was preparet wyt e ollowing ree- (H7 43 65 1pc: 17-11 Q 0.10 351(660 10 1.0

Homopolymcr Recipe Rubber 1 Q R S '1 (y-elohexane. phm 722 722 722 722712 Buladiene. ph\\' 100 100 I00 100 'letrahydroluran. plnn (1.1 0.1(1.1 (1.1 0.1 n-But \'1lithiun1. 11111111 (15 1.11 1.5 2.0 3.0 Po1\n1eri/a1ion 'lemp. (I 70 7O 70 70 70 l1\l \1neri/ation lime. hrs. 1 1 lI 1 (oupling Agent. 11111111 (1 05"" (1.025 0.5"" lh-dht-bnt l-4-n1ethlphenol. plnn 1.0 1.0 Lo 1.0 1.0

""l)1lllk.'lll}1\1l\:l|1l11"1 \1llll\u "".\Ielh \ltrielilmuwlam:'SIlieon letraehlorille. 11 .uhlcd in one ine1e|nen1 lolloned 1 fourineremenls 011111113 each added :11 one nnnute inlenals""l1e\.|e|11u11ulisllane The polybutadienes P through T were subjectedto 17-h 0.25 321 5x00 79 6.5 R 0. a 351 (350 11 1.0 graft polymerlzationin a suspension system employing U l 0 g 8 6 0 70/30styrene/aerylonitrile monomer mixture as de- 19 0.30 337 (13110 7 1.0 1.i n H- 55 19,11 (1.56 307 5x90 37 5.1 scr1bed betore. except employing ll. eight percent 20% T 052 34] 6740 7 04 of polybutadiene rubber andthebalance styrene/a- 77 331 x 7 4,11 crylonitrile mixture. Otherwise thesame suspension polymerization recipe was employed. and thecorresponding grafted copolymers 16 through 20 respeci v Thenonsuitability of polybutadiene branched or otherwise as the'rubberycomponent is illustrated by the low lzod impact values-in the runs16-11. 17-a. l8-a.

19-21. 20-21 abovev Polymer stabilizers. e.g.. antioxidants. can beadded '65 either before'or'afte r polymerization. and either before orafter'thehot'mixing step-(depending upon the type ofantioxidantemployed. The polymers can be compounded with a wide varietyof fillers. plasticizers. pigments, reinforcing fibers and the like, for\arious purposes.

Certainly, reasonable variations andmodifications of our invention arepossible yet still within the scope of our disclosure and withoutdeparting from the intended scope and spirit thereof.

We claim:

1. A process for the preparation of high impact plas tic compositionswhich comprises the steps of;

polymerizing at least one polymerizable monovinyl-substituted aromaticcompound employing an organo monoalkali metal initiator underpolymerization conditions, thereby forming a block of saidmonovinyl-substituted aromatic compound. b. further polymerizing ontothe monovinylsubstituted aromatic compound polymer block fromsaid step(a) at least one copolymerizablc conjugated diene, thereby forming ontosaid block of monovinyl-substituted aromatic compound polymer a block ofpolymerized conjugated dicne with a carbon-lithium bond on the endthereoil wherein the resulting block copolymer contains about 40 to 95parts by weight copolymerized conjugated diene and correspondingly about(7U to parts by weight copolymcrizcd monoyinylsubstituted aromaticcompound. said copolymer characterized by sufiicient unsaturation as tobe vulcanizable, reacting the block copolymer from said step (b) with apolyfunctional compound containing 3 to 7 reactive sites per moleculecapable of reacting with the carbon-lithium bond on the end of theconjugated diene block of the copolymer prepared in said step (b), saidpolyfunctional compound is selectcd from the group consisting ofepoxides, isocyanates, imines, aldehydes, and halides, thereby preparinga radial block copolymer characterized in that the end blocks arederived from said monovinyl-substituted compound.

d. dissolving the radial block copolymer resulting from said step (c) inat least one vinylidenc group containing monomer selected from the groupconsisting of monovinyl-substituted aromatic compounds, alpha.beta'unsaturated nitrilcs, esters of acrylic acid, esters of alkacrylicacid, vinyl esters. maleinimides, dialkyl maleates, dialkyl fumarates,or mixtures, of which a vinylidine nitrile monomer constitutes up toabout 95 weight percent, wherein said vinylidene group containingmonomer contains up to carbon atoms per molecule, thereby preparing arubbcr-in-monomer solution,

e. suspension polymerizing under aqueous suspension polymerizationconditions said rubberinmonomer solution,

f. recovering the product of said aqueous suspension polymerization as ahigh impact plastic composition.

2. The process according to claim 1 wherein in said step (d) saidcopolymer from said step (c) represents about 5 to percent by weightbased on the combined weight of copolymer and vinylidcnc groupcontaining monomer in said step (d).

3. The process according to claim 1 wherein said vinylidenc nitrilecontaining monomer comprises acrylonitrile.

l4 4; The process according to claim 3 wherein said vinylidehe groupcontaining monomers comprise acrylonitril e and styrene, and saidbranchedblock copolymer is a copolymer of butadicne and styrene. 5.lnthc preparation ofhigh impact plastic compositions wherein anunsaturated rubbery copolymer is dissolved inat least one vinylidcnegroupcontaining monomer and thereafter suspension polymerized underaqueous suspension polymerization conditions employing ,a free radicalinitiator. the improvement which comprises employing as said rubberycopolymer an unsaturated branched block copolymer of at least onepolymerizable conjugated dicne and at least one copolymerizablemonovinyl-substituted aromatic compound charactcrizcd as a radical blockcopolymer prepared by polymerizing a monovinyl-substituted aromaticcompound monomer under polymerization conditions employing anorgano-alkali metal initiator. thereby forming a block of saidmonovinylaromatic compound monomer, polymerizing thereon a block of atleast one polymerizable conjugated dicnc. thereby producing blockcopolymer. and thereafter branching said block copolymer with apolyfunctional treating agent containing at least three reactive sitesper molecule reactable with a carbon-lithium bond and selected from thegroup, consisiting of polyepoxides, polyisocyanates, polyimines.polyaldehydes, and polyhalides thereby producing a branched blockcopolymer. wherein the end blocks of said branched block co polymers aresaid mono inyl-substituted aromatic compound blocks. and the degree ofunsaturation in said unsaturated branched block polymer is characterizedas sufficient to be vulcanizablc; and wherein said inylidenc groupcontaining mono mcr in said suspension is selected from the groupconsisting of monovinyl-substituted aromatic coinpoundsialpha,bcta-unsaturated nitriles, esters of acrylic acid, esters ofallsacrylic acid and vinyl esters, containing Lip to IR carbon atoms permolecule.

6. The process according to claim 5 wherein said branched blockcopolymer is characterized as at least three copolymer blocks branchingfrom nuclei formed by polyfunctional compounds,

wherein said polymerizable conjugated diene contains 4 to 12 carbonatoms per molecule, and said copolymerizable monovinyl-substitutedaromatic compound contains is to 20 carbon atoms per molecule.

7. The process according to claim 6 wherein each said copolymer blockcontains about 40 to 95 phm polymerized conjugated dicnc andcorrespondingly about to 5 phm copolymerizcd monovinyl-substitutcdaromatic compound.

8. The process according to claim 7 wherein said polyfunctional treatingagent contains 3 to 7 reactive sites per molecule.

9. The process according to claim 7 wherein is employed about 5 to 40weight percent of said unsaturated branched block copolymer based on thecombined weight of branched block copolymer and vinylidene groupcontaining monomer.

10. The process aeeord ing to claim 7 wherein said vinylidene groupcontaining monomer includes at least one monovinyl-substituted aromaticmonomer and. at least one alpha,beta-un'saturated nitrile.

11. The process according to claim 10 wherein saidalpha,beta-unsaturatcd nitrile monomer constitutes up' to 95 weightpercent of the \iinylidene group containing monomer excluding saidbranched-block copolymer.

12. The process according to claim vll wherein said vinylidene groupcontaining monomer contains .upto 50 weight percentalpha,beta-unsaturated nitrile monomet and correspondingly up to 50weight percent of monovinyl-substituted aromatic monomer.

l3.-The process according to claim 11 wherein saidalpha,beta-unsaturated nitrile isacrylonitrile,.and saidmonovinyl-substituted aromatic monomer is styrene.

b'ran ched block copolymer is a butadiene/styrene 75/25 copolymerbranched with silicontetrachloridc.

17. The process according to claim 14 wherein said branched blockcopolymer is a butadiene/styrene 75/25 copolymer branched withhexachlorodisilane.

18. The "process according to claim 12 wherein said monomer mixture isabout /30 weight ratio styrene/acrylonitrile.

19. The process according to claim 8 .wherein the number of branches ofsaid branched block copolymer ranges from 3 to 6.

20. The process-according to claim 19 wherein the number of branches isapproximately 3.

21. The process according to claim 8 wherein said high impactcomposition is recovered from said'suspension polymerization and hotmixed in the absence of cross-linking agent. 4 I

'22. The process according to claim 21 wherein said hot-mixedhighimpac't composition further is compounded with at least one filler,plasticizer. pigment.

reinforcing fiber, or mixture.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT NO. I 3,903,201 DATED September 2 1975 INVENT Clifford w.Childers; Earl Clark- It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

' Column 14, claim 5, line 17, "radical" should read radial line 29,"consisiting" should read consisting Engned and Sealed thls sixth D y ofJanuary 1976 [SEAL] Attest:

: RUTH C. MASON c. MARSHALL DANN Arresting Officer (ummissimwroj'Parents and Trademarks

1. A PROCESS FOR THE PREPARATION OF HIGH IMPACT PLASTIC COMPOSITIONSWHICH COMPRISES THE STEPS OF: A. POLYMERIZING AT LEAST ONE POLYMERIZABLEMONOVINYL-SUBSTITUTED AROMATIC COMPOUND EMPLOYING AN ORGANO MONOALKALIMETAL INITIATOR UNDER POLYMERIZATION CONDITIONS, THEREBY FORMING A BLOCKOF SAID MONOVINYL-SUBSTITUTED AROMATIC COMPOUND, B. FURTHER POLYMERIZINGONTO THE MONOVINYL-SUBSTITUTED AROMATIC COMPOUND POLYMER BLOCK FROM SAIDSTEP (A) AT LEAST ONE COPOLYMERIZABLE CONJUGATED DIENE, THEREBY FORMINGONTO SAID BLOCK OF MONOVINYL-SUBSTITUTED AROMATIC COMPOUND POLYMER ABLOCK OF POLYMERIZED CONJUGATED DIENE WITH A CARBON-LITHIUM BOND ON THEEND THEREOF, WHEREIN THE RESULTING BLOCK COPOLYMER CONTAINS ABOUT 40 TO95 PARTS BY WEIGHT COPOLYMERIZED CONJUGATED DIENE AND CORRESPONDINGLYABOUT 60 TO 5 PARTS BY WEIGHT COPOLYMERIZED MONOVINYL-SUBSTITUTEDAROMATIC COMPOUND, SAID COPOLYMER CHARACTERIZED BY SUFFICIENTUNSATURATION AS TO BE VULCANIZABLE, C. REACTING THE BLOCK COPOLYMER FROMSAID STEP (B) WITH A POLYFUNCTIONAL COMPOUND CONTAINING 3 TO 7 REACTIVESITES PER MOLECULE CAPABLE OF REACTING WITH THE CARBON-LITHIUM BOND ONTHE END OF THE CONJUTATED DIENE BLOCK OF THE COPOLYMER PREPARED IN SAIDSTEP (B), SAID POLYFUNCTIONAL COMPOUND IS SELECTED FROM THE GROUPCONSISTING OF EPOXIDES, ISOCYANATES, IMINES, ALDEHYDES, AND HALIDES,THEREBY PREPARING A RADIAL BLOCK COPOLYMER CHARATERIZED IN THAT THE ENDBLOCKS ARE DERIVED FROM SAID MONOVINYL-SUBSTITUTED COMPOUND, D.DISSOLVING THE RADIAL BLOCK COPOLYMER RESULTING FROM SAID STEP (C) IN ATLEAST ONE VINYLIDENE GROUP CONTAINING MONOMER-SELECTED FROM THE GROUPCONSISTING OF MONOVINYL-SUBSTITUTED AROMATIC COMPOUNDS, ALPHA,BETA-UNSATURATED NITRILES, ESTER OF ACRYLIC ACID, ESTERS OF ALKACRYLICACID, VINYL ESTERS, MALEINIMIDES, DIALKYL MALEATES, FUMARATES, ORMIXTURES, OF WHICH A VINYLIDINE NITRILE MONOMER CONSTITUTES UP TO ABOUT95 WEIGHT PERCENT, WHEREIN SAID VINYLIDENE GROUP CONTAINING MONOMERCONTAINS UP TO 30 CARBON ATOMS, PER MOLECULE, THEREBY PREPARING ARUBBERIN-MONOMER SOLUTION, E. SUSPENSION POLYMERIZING UNDER AQUEOUSSUSPENSION POLYMERIZATION CONDITIONS SAID RUBBER-IN-MONOMER SOLUTION, F.RECOVERING THE PRODUCT OF SAID AQUEOUS SUSPENSION POLYMERIZATION AS AHIGH IMPACT PLASTIC COMPOSITION.
 2. The process according to claim 1wherein in said step (d) said copolymer from said step (c) representsabout 5 to 40 percent by weight based on the combined weight ofcopolymer and vinylidene group containing monomer in said step (d). 3.The process according to claim 1 wherein said vinylidene nitrilecontaining monomer comprises acrylonitrile.
 4. The process according toclaim 3 wherein said vinylidene group containing monomers compriseacrylonitrile and styrene, and said branched block copolymer is acopolymer of butadiene and styrene.
 5. In the preparation of high impactplastic compositions wherein an unsaturated rubbery copolymer isdissolved in at least one vinylidene group containing monomer andthereafter suspension polymerized under aqueous suspensionpolymerization conditions employing a free radical initiator, theimprovement which comprises employing as said rubbery copolymer anunsaturated branched block copolymer of at least one polymerizableconjugated diene and at least one copolymerizable monovinyl-substitutedaromatic compound characterized as a radical block copolymer prepared bypolymerizing a monovinyl-substituted aromatic compound monomer underpolymerization conditions employing an organo-alkali metal initiator,thereby forming a block of said monovinyl-aromatic compound monomer,polymerizing thereon a block of at least one polymerizable conjugateddiene, thereby producing block copolymer, and thereafter branching saidblock copolymer with a polyfunctional treating agent containing at leastthree reactive sites per molecule reactable with a carbon-lithium bondand selected from the group consisiting of polyepoxides,polyisocyanates, polyimines, polyaldehydes, and polyhalides therebyproducing a branched block copolymer, wherein the end blocks of saidbranched block copolymers are said monovinyl-substituted aromaticcompound blocks, and the degree of unsaturation in said unsaturatedbranched block polymer is characterized as sufficient to bevulcanizable; and wherein said vinylidene group containing monomer insaid suspension is selected from the group consisting ofmonovinyl-substituted aromatic compounds, alpha,beta-unsaturatednitriles, esters of acrylic acid, esters of alkacrylic acid, and vinylesters, containing up to 18 carbon atoms per molecule.
 6. The processaccording to claim 5 wherein said branched block copolymer ischaracterized as at least three copolymer blocks branching from nucleiformed by polyfunctional compounds, wherein said polymerizableconjugated diene contains 4 to 12 carbon atoms per molecule, and saidcopolymerizable monovinyl-substituted aromatic compound contains 8 to 20carbon atoms per molecule.
 7. The process according to claim 6 whereineach said copolymer block contains about 40 to 95 phm polymerizedconjugated diene and correspondingly about 60 to 5 phm copolymerizedmonovinyl-substituted aromatic compound.
 8. The process according toclaim 7 wherein said polyfunctional treating agent contains 3 to 7reactive sites per molecule.
 9. The process according to claim 7 whereinis employed about 5 to 40 weight percent of said unsaturated branchedblock copolymer based on the combined weight of branched block copolymerand vinylidene group containing monomer.
 10. The process according toclaim 7 wherein said vinylidene group containing monomer includes atleast one monovinyl-substituted aromatic monomer and at least onealpha,beta-unsaturated nitrile.
 11. The process according to claim 10wherein said alpha,beta-unsaturated nitrile monomer constitutes up to 95weight percent of the vinylidene group containing monomer excluding saidbranched block copolymer.
 12. The process according to claim 11 whereinsaid vinylidene group containing monomer contains up to 50 weightpercent alpha, beta-unsaturated nitrile monomer and correspondingly upto 50 weight percent of monovinyl-substituted aromatic monomer.
 13. Theprocess according to claim 11 wherein said alpha,beta-unsaturatednitrile is acrylonitrile, and said monovinyl-substituted aromaticmonomer is styrene.
 14. The process according to claim 13 wherein saidradial branched block copolymer is a copolymer of butadiene/styrenebranched with a polyhalide.
 15. The process according to claim 14wherein said branched block copolymer is a butadiene/styrene 75/25copolymer branched with methyltrichlorosilane.
 16. The process accordingto claim 14 wherein said branched block copolymer is a butadiene/styrene75/25 copolymer branched with silicontetrachloride.
 17. The processaccording to claim 14 wherein said branched block copolymer is abutadiene/styrene 75/25 copolymer branched with hexachlorodisilane. 18.The process according to claim 12 wherein said monomer mixture is about70/30 weight ratio styrene/acrylonitrile.
 19. The process according toclaim 8 wherein the number of branches of said branched block copolymerranges from 3 to
 6. 20. The process according to claim 19 wherein thenumber of branches is approximately
 3. 21. The process according toclaim 8 wherein said high impact composition is recovered from saidsuspension polymerization and hot mixed in the absence of cross-linkingagent.
 22. The process according to claim 21 wherein said hot-mixed highimpact composition further is compounded with at least one filler,plasticizer, pigment, reinforcing fiber, or mixture.